When I try to open my .mpp files that I created with Project 2010, I get an error message indicating that the 2007 version (I doesn’t have Office 2007 on my PC) is trying to open them and that I need to install a converter. Any suggestions on how I can make 2010 to open my Project files? (I'm running Windows 7, if that matters.)

If you MUST use MS Office then right click the file and try the open with option to browse for the project 2010 exe and see if ti opens that way. Basically make sure the file association is set to open with the actual version you are using rather than another exe file on the computer.

Did you have the 2007 version installed before? Did you use a standalone player/viewer?

You will need to follow these steps exactly to make the 2010 version default. Right-click on your .mpp file and select Open With. Then select "Choose default program"Then select 2010 version from list, if it's not there use Browse button to point to 2010 versionthen place a chekmark on "Always use this program to open this kind of file"then click OK.In case if the file is corrupted then it is possible to try to recover with Project Recovery Toolbox http://www.oemailrecovery.com/project_recovery.html